1. Field of the Invention
This invention relates to an improvement on an electronic flash apparatus of the automatic light control type having first and second flash discharge tubes.
2. Description of the Prior Art
In a photographing art called bounce photography, a flash light of an electronic flash device is arranged to be reflected by a ceiling or a wall for photographing illumination. However, in cases where an object to be photographed is, for example, a person or the like, it is sometimes hardly possible to obtain a lively picture due to a shade produced on the lower half of the face, disappearance of light from eyes, etc. To solve this problem, there have been proposed electronic flash devices of the kind having two flash discharge tubes, one for indirect bounce illumination and the other for direct front illumination.
An example of these prior art devices which has been disclosed by Japanese Utility Model Laid-Open Application No. Sho 55-164624 is arranged as shown in FIGS. 1 and 2 of the drawings annexed hereto. In the prior art device, a flash discharge tube 1 for bounce illumination, another flash discharge tube 2 for direct illumination and a thyristor 3 are connected in series. Another thyristor 4 or 5 is connected either in parallel with the flash discharge tube 2 or in parallel with the series circuit of the flash discharge tube 2 and the thyristor 3. The flash discharge tubes 1 and 2 are arranged to simultaneously begin to flash when the thyristor 3 is energized. When the quantity of light received reaches a first prescribed level which is of a relatively small value, the thyristor 4 or 5 is energized to stop the direct illuminating flash discharge tube 2 from flashing. Then, when the received light quantity reaches a second prescribed level which is set at a value required for an appropriate exposure, the thyristor 3 or 5 becomes non-conductive to stop the bounce illuminating flash discharge tube 1 from flashing.
The electronic flash device of this kind necessitates use of a plurality of switching elements for controlling flashing currents, as indicated by the thyristors 3 and 4 in FIG. 1 and by thyristors 3 and 5 in FIG. 2. This arrangement of the prior art thus has resulted in a complex circuit.